Class: BaseObject

Abstract base class; normally only used for creating subclasses and not
instantiated in apps.
Most non-trivial classes inherit from this.

This extends module:ol/Observable with observable
properties, where each property is observable as well as the object as a
whole.

Classes that inherit from this have pre-defined properties, to which you can
add your owns. The pre-defined properties are listed in this documentation as
'Observable Properties', and have their own accessors; for example,
module:ol/Map~Map has a target property, accessed with
getTarget() and changed with setTarget(). Not all properties are however
settable. There are also general-purpose accessors get() and set(). For
example, get('target') is equivalent to getTarget().

The set accessors trigger a change event, and you can monitor this by
registering a listener. For example, module:ol/View~View has a
center property, so view.on('change:center', function(evt) {...}); would
call the function whenever the value of the center property changes. Within
the function, evt.target would be the view, so evt.target.getCenter()
would return the new center.

You can add your own observable properties with
object.set('prop', 'value'), and retrieve that with object.get('prop').
You can listen for changes on that property value with
object.on('change:prop', listener). You can get a list of all
properties with module:ol/Object~BaseObject#getProperties.

Note that the observable properties are separate from standard JS properties.
You can, for example, give your map object a title with
map.title='New title' and with map.set('title', 'Another title'). The
first will be a hasOwnProperty; the second will appear in
getProperties(). Only the second is observable.

Properties can be deleted by using the unset method. E.g.
object.unset('foo').